For a few years now, Chipotle has regarded traditional marketing as largely irrelevant for its needs. But the one TV buy it made this year -- its first national TV ad, no less -- garnered more attention than most marketers dream of getting.

The funny thing is , it was was never intended to be a TV spot. "Back to the Start" began life in summer 2011 as a two-minute online video, but Chief Marketing Officer Mark Crumpacker said it got such a great reception online that Chipotle decided to buy media around it. So in fall 2011, the video aired in some 5,700 movie theaters.

"People were applauding [in the theaters]," said Mr. Crumpacker. He knew the chain needed to do something bigger, so the company decided to buy time during this year's Grammys to air the entire piece.

"Back to the Start," which features a Willie Nelson cover of Coldplay's "The Scientist" and was created by Creative Artists Agency, tells the story of one pig farmer's journey from running a huge industrialized farming compound to the farmer realizing that he needed to farm using more-sustainable and humane practices. It was a hit.

"I don't know that it was anything other than what we did, [which was] make a story that resonated with people," Mr. Crumpacker said of the ad's success.

In 2011, systemwide sales were up 23.4%, according to Technomic. It's also performed better than nearly all other chains in recent years. And all of it was acccomplished with very little measured-media spending. Chipotle spent just $5.8 million on measured media last year, according to Kantar Media. That's down from $7.5 million in 2010.

As such, the chain isn't going to jump into a huge media buy blindly. "It's pretty easy to figure out whether something's popular before you go and buy media around it," said Mr. Crumpacker. "It wasn't as easy before without social media ... the plan is to put them out there and see how well they do."

He cautioned, though, that when it comes to messages, "one of the things we learned is to be very truthful and accurate in the things we're doing." Mr. Crumpacker said that with "Back to the Start," Chipotle felt it was an allegory, whereas "a lot of people felt that was an ad making specific claims." The Better Business Bureau challenged Chipotle to prove specific claims, which Mr. Crumpacker said it was able to do, and the BBB concurred.

"But it taught me that while we think we're telling a simple story, the people watching it are taking a lot away from it, and if you're not careful they may take something away that you weren't expecting," he said. "You don't want people turning against you."